The present invention relates to a powder dispersing apparatus, and more particularly to a powder dispersing apparatus that can generate floating powder required in examining the properties of powder and supply the floating powder to a powder measuring device or the like.
In recent years, it has been increasingly required to examine not only the macroscopic properties of powder as an aggregate, but also the microscopic properties of powder particles as the characteristics of powder. In examining the microscopic properties of powder particles, it is necessary to measure the particle size, shape, and electric charge, etc. of each powder particle. Conventionally, the powder could be classified according to its particle sizes by using a sieve or the like. In recent years, however, the particle sizes of powder have been greatly inclined to become very small, and the study on powder particles having a particle size of about 1 to 2 .mu.m or less has been increasingly made. It is needless to say that such fine powder cannot be classified by using a sieve.
To measure the particle size of such fine powder without the use of a sieve mesh, a powder measuring device or the like is used to direct a laser beam or any other light beams onto one powder particle and produce a video image by reflection, projection, or photography. Such a powder measuring device requires an apparatus capable of completely isolating the powder particles from each other, i.e., a powder dispersing apparatus. Accordingly, it is greatly desired to provide an apparatus capable of producing floating powder as fine particles and making the concentration thereof constant as one means for completely isolating the powder particles.
To produce such floating powder, a small amount of powder must be dispersed in a large amount of gas. As means for supplying powder to the powder dispersing apparatus, a screw feeder or a vibrating feeder is generally used. However, since the screw feeder and the vibrating feeder are large in size, a large amount of sample powder is required to produce a given amount of floating powder. Conversely, if the size of the feeder is made small, a minimum amount of floating powder such as several grams per hour to several tens of grams per hour required for examination of powder cannot be supplied constantly.
Further, as means for mixing the powder supplied to the powder dispersing apparatus into a given gas flow, an ejector is normally used. However, the ejector causes large pulsation, so that a gas flow with a constant concentration of dispersed powder cannot be generated. Furthermore, since dispersion pressure is also low, the degree of dispersion becomes insufficient.